Moon Jellies

Prepare to be mesmerized, by stepping into the Aquarium's jellies exhibit, featuring Moon Jellies and Pacific Sea Nettles.

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Moon Jellies, Aurelia aurita

Fast Facts

Worldwide, there are more than 200 species of jellies.

Jellies are made up of 95% water and have no heart, brains, or bones.

Movement is primarily controlled by bay and ocean currents, even though they do “pulsate.”

Fun Fact

Aquarium of the Bay has cultured Moon jellies in-house since 1998. For an up-close look at the life cycle of a Moon jelly, register for a Behind the Scenes tour.

Go Deeper!
Worldwide, there are more than 200 species of jellies. Jellies are made up of 95% water and have no heart, brains, or bones. They have a complex set of nerves that respond to stimuli, but they do not process thoughts. Instead of receiving oxygen through lungs, gills, or other respiratory systems, they diffuse oxygen through a thin membrane. Their bodies pulse through the waters, but movement is primarily controlled by Bay and ocean currents.

Named for their translucent coloring and resemblance to Earth’s satellite, moon jellies are found in temperate and tropical waters worldwide, including along the Northern California coast. The species also traveled far beyond its underwater confines in 1991, when more than 1,000 moon jellies flew aboard the space shuttle Columbia, as part of a study on weightlessness and how it effects the development of juvenile jellies.

“Moon jellies are one of the most primordial marine creatures, yet they don’t look like they should be alive,” said Michael Grassmann, Senior Biologist at Aquarium of the Bay. “Their calming presence, combined with alien-like looks makes them visitor favorites.”

Moon jellies are found in temperate and tropical waters worldwide, including along the Northern California coast. Moon jellies are a fast growing and fairly short-lived species, developing from the larvae or planula stage to their adult or medusa phase in approximately 10 months. While jellies in the wild typically only live to one year old, due to predation by animals including turtles and other jellies, they can survive much longer at aquariums where they are protected and closely monitored.

Jelly species are being directly affected by climate change. Jelles thrive in warmer waters, so as water temperatures continue to rise, jelly populations and range increase. Information about this increase in jelly populations, referred to as jelly blooms, is shared with guests in the Aquarium's "Go With the Flow" exhibit.

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